SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b55f0de6ac513a4ea4b21fe452eb017c4d202b05654c49e3fc4b2b06d41767be' 
  AND token = 'qRGzTGqIBPb+Lfb7Yc7UpllhwFzFxyXjGncxSzGMhHE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}